Q: In this task, you are given an article. Your task is to summarize the article in a sentence.
He made the announcement at a press conference on Wednesday morning, after visiting Mr Buhari at the London hospital where he is being treated for an unspecified illness.
Mr Osinbajo, now back in Nigeria, said he had discussed a wide range of issues during the hour-long meeting.
Mr Buhari has been in London since May.
Africa Live: Updates on this and other stories
The 74-year-old leader was elected to power in 2015, becoming the first Nigerian  opposition leader to win an election.
It is his second period of medical leave in the UK, the first began in January and he returned home in March.
His long absence has led to speculation about whether he will be able to resume his presidential duties.
In his absence, President Buhari has given Vice-President Osinbajo full powers to act, in contrast to the situation in 2009, when the long illness of then President Umaru Yar'Adua led to a power vacuum.
By Ibrahim Shehu, BBC Hausa, Abuja
Nigerians are becoming increasingly sceptical about President Buhari's fitness to continue to govern the country effectively.
His indefinite medical leave and the economy in recession means the hope and aspirations of the electorate who brought him to power more than two years ago have died.
The uncertainty surrounding Mr Buhari's ability to continue to govern, or stand in elections in 2019, has left a lot of his political associates and supporters in limbo, as campaigning for 2019 begins in earnest a year from now.
Earlier this week, Nigeria's first lady Aisha Buhari launched a cryptic attack, apparently aimed at powerful ruling party politicians suspected of manoeuvring for the presidency or deputy presidency while her husband was ill.
In a Facebook post, Mrs Buhari warned that "hyenas and jackals" would be banished.
The vice-president has been acting in Mr Buhari's place while he is out of the country, but there is no suggestion he is part of any plot against the leader, says the BBC's Naziru Mikailu.
Mrs Buhari's comments came in response to a post from Senator Shehu Sani, who warned that people were "scheming... so that they can be kings".
"Prayers for the absent Lion King has waned," he wrote. "Now the hyenas and the jackals are scheming and talking to each other in whispers; still doubting whether the Lion King will be back or not."
But Mrs Buhari appeared to calm any concerns - suggesting her husband, positioned as the defender of the "weaker animals", was on the mend.
"God has answered the prayers of the weaker animals, the hyenas and jackals will soon be sent out the kingdom."
A:
President Muhammadu Buhari is "recuperating fast" and will return home "very soon", says Nigeria's acting head of state Yemi Osinbajo.